On Thu, 10 Sep 2020 03:45:18 -0700 Liu Yi L <[email protected]> wrote:
> IOMMUs that support nesting translation needs report the capability info > to userspace. It gives information about requirements the userspace needs > to implement plus other features characterizing the physical implementation. > > This patch introduces a new IOMMU UAPI struct that gives information about > the nesting capabilities and features. This struct is supposed to be returned > by iommu_domain_get_attr() with DOMAIN_ATTR_NESTING attribute parameter, with > one domain whose type has been set to DOMAIN_ATTR_NESTING. > > Cc: Kevin Tian <[email protected]> > CC: Jacob Pan <[email protected]> > Cc: Alex Williamson <[email protected]> > Cc: Eric Auger <[email protected]> > Cc: Jean-Philippe Brucker <[email protected]> > Cc: Joerg Roedel <[email protected]> > Cc: Lu Baolu <[email protected]> > Signed-off-by: Liu Yi L <[email protected]> > Signed-off-by: Jacob Pan <[email protected]> > --- > v6 -> v7: > *) rephrase the commit message, replace the @data[] field in struct > iommu_nesting_info with union per comments from Eric Auger. > > v5 -> v6: > *) rephrase the feature notes per comments from Eric Auger. > *) rename @size of struct iommu_nesting_info to @argsz. > > v4 -> v5: > *) address comments from Eric Auger. > > v3 -> v4: > *) split the SMMU driver changes to be a separate patch > *) move the @addr_width and @pasid_bits from vendor specific > part to generic part. > *) tweak the description for the @features field of struct > iommu_nesting_info. > *) add description on the @data[] field of struct iommu_nesting_info > > v2 -> v3: > *) remvoe cap/ecap_mask in iommu_nesting_info. > *) reuse DOMAIN_ATTR_NESTING to get nesting info. > *) return an empty iommu_nesting_info for SMMU drivers per Jean' > suggestion. > --- > include/uapi/linux/iommu.h | 76 > ++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 76 insertions(+) > > diff --git a/include/uapi/linux/iommu.h b/include/uapi/linux/iommu.h > index 1ebc23d..ff987e4 100644 > --- a/include/uapi/linux/iommu.h > +++ b/include/uapi/linux/iommu.h > @@ -341,4 +341,80 @@ struct iommu_gpasid_bind_data { > } vendor; > }; > > +/* > + * struct iommu_nesting_info_vtd - Intel VT-d specific nesting info. > + * > + * @flags: VT-d specific flags. Currently reserved for future > + * extension. must be set to 0. > + * @cap_reg: Describe basic capabilities as defined in VT-d capability > + * register. > + * @ecap_reg: Describe the extended capabilities as defined in VT-d > + * extended capability register. > + */ > +struct iommu_nesting_info_vtd { > + __u32 flags; > + __u64 cap_reg; > + __u64 ecap_reg; > +}; The vendor union has 8-byte alignment, so flags here will be 8-byte aligned, followed by a compiler dependent gap before the 8-byte fields. We should fill that gap with padding to make it deterministic for userspace. Thanks, Alex > + > +/* > + * struct iommu_nesting_info - Information for nesting-capable IOMMU. > + * userspace should check it before using > + * nesting capability. > + * > + * @argsz: size of the whole structure. > + * @flags: currently reserved for future extension. must set to 0. > + * @format: PASID table entry format, the same definition as struct > + * iommu_gpasid_bind_data @format. > + * @features: supported nesting features. > + * @addr_width: The output addr width of first level/stage translation > + * @pasid_bits: Maximum supported PASID bits, 0 represents no PASID > + * support. > + * @vendor: vendor specific data, structure type can be deduced from > + * @format field. > + * > + * +===============+======================================================+ > + * | feature | Notes | > + * +===============+======================================================+ > + * | SYSWIDE_PASID | IOMMU vendor driver sets it to mandate userspace | > + * | | to allocate PASID from kernel. All PASID allocation | > + * | | free must be mediated through the IOMMU UAPI. | > + * +---------------+------------------------------------------------------+ > + * | BIND_PGTBL | IOMMU vendor driver sets it to mandate userspace to | > + * | | bind the first level/stage page table to associated | > + * | | PASID (either the one specified in bind request or | > + * | | the default PASID of iommu domain), through IOMMU | > + * | | UAPI. | > + * +---------------+------------------------------------------------------+ > + * | CACHE_INVLD | IOMMU vendor driver sets it to mandate userspace to | > + * | | explicitly invalidate the IOMMU cache through IOMMU | > + * | | UAPI according to vendor-specific requirement when | > + * | | changing the 1st level/stage page table. | > + * +---------------+------------------------------------------------------+ > + * > + * data struct types defined for @format: > + * +================================+=====================================+ > + * | @format | data struct | > + * +================================+=====================================+ > + * | IOMMU_PASID_FORMAT_INTEL_VTD | struct iommu_nesting_info_vtd | > + * +--------------------------------+-------------------------------------+ > + * > + */ > +struct iommu_nesting_info { > + __u32 argsz; > + __u32 flags; > + __u32 format; > +#define IOMMU_NESTING_FEAT_SYSWIDE_PASID (1 << 0) > +#define IOMMU_NESTING_FEAT_BIND_PGTBL (1 << 1) > +#define IOMMU_NESTING_FEAT_CACHE_INVLD (1 << 2) > + __u32 features; > + __u16 addr_width; > + __u16 pasid_bits; > + __u8 padding[12]; > + /* Vendor specific data */ > + union { > + struct iommu_nesting_info_vtd vtd; > + } vendor; > +}; > + > #endif /* _UAPI_IOMMU_H */ _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
